Boar-taint is a major economic problem for the pork industry. Although only about 5 to 10% of male pigs are affected, the taint, an offensive, fecal smell associated with poor meat tenderness and often a bitter taste, is not detected until the meat is cooked. Because pigs having the taint are not readily distinguishable from unaffected pigs, pork producers castrate all male pigs at an early age. That procedure is costly and time consuming. Moreover, the castrated pigs suffer from retarded weight gain and decreased lean meat content. The process thus results in higher costs of pork production and hence higher cost for consumers.
Studies have shown that the contents of androstenone and skatole (3-methylindole) present in the carcass have a strong correlation to the unpleasant odor in the meat (Hansson et al., Swedish J. Agric. Res. (1980) 10:167-173: Walstra et al., Res. Inst. for Animal Prod. "Schoonoord", Zeist, The Netherlands, "The androstenone-skatole as applied in a consumer test": and Mortensen and Sorensen Proc. of the Danish Meat Res. Inst., "Relationship between boar taint and skatole determined with a new analysis method" (Apr. 5, 1984, Manuscript No. 661E). Indole, albeit in low concentration, is also reported to be present in boartaint (Hansson et al., supra). Evidence suggests that the skatole content of fat provides an estimate of the adverse odor, tenderness and overall taste for the meat (Mortensen et al., Proc. of the Danish Meat Res. Inst. (1986) 1:4,23-26). In particular, when the skatole content of the carcass body fat exceeds about 0.25 to 0.30 ppm, the pork has an offensive odor when cooked (Mortensen et al., supra).
At the present time, there is an analytical procedure that estimates skatole concentration in carcass fat by a colorimetric procedure (Mortensen and Sorensen, supra). The method is based on determining the concentration of a colored product produced when an indole derivative reacts with p-dimethylaminobenzaldehyde. The procedure is involved, utilizing a number of steps including grinding the sample, extracting skatole from fat with organic solvents, filtration and the colorimetric reaction. A major disadvantage of the method is that it does not provide the true skatole concentration, but rather indicates total indole derivatives present in the sample. Although skatole is expected to constitute a large percentage of the indole derivatives present, tryptophan, an amino acid present in proteins, is also detected by the assay method. Chromatographic analyses on the extracts have also been reported. See Garcia-Regueiro et al., J. High Resolution Chromat. & Chromat. Comm. (1986) 9:362-363.
A rapid, easy to perform assay that accurately determines tainted pigs would allow producers to discard affected carcasses at slaughter rather than castrate all boars at an early age.
Relevant Literature
Hansson et al., Swedish J. Agric. Res. (1980) 10:167-173 and Walstra et al., Res. Inst. for Animal Prod. "Schoonoord", Zeist, The Netherlands, "The androstenone-skatole as applied in a consumer test" report that boar taint correlates with ansdrostenone and skatole. Mortensen and Sorensen, Proc. of the Danish Meat Res. Inst., "Relationship between boar taint and skatole determined with a new analysis method" (Apr. 5, 1984) Manuscript No. 661E describe a colorimetric analysis for the determination of skatole in extracts of adipose tissue. Mortensen et al., Proc. of the Danish Meat Res. Inst. (1986) 1:4,23-26 report backfat skatole concentrations correlated with boat taint.